What is a Graphic Equalizer


Graphic equalizers are one of the simplest types of equalizers available. They usually consist of multiple graphical sliders and other controls that producers use for altering and controlling the frequency response of an audio system. Graphic equalizers mostly boost or cut the frequencies of the sound signal. Additionally, they help in shaping the audio output and making the best use of the digital music library and speaker setup of specific audio systems.


How does it work?


A technology behind graphic equalizer works like a series of filters. The input signal passes through each filter of a particular frequency, and when one changes the slider positions, it boosts or cuts the frequency components of the signal. The vertical position of each slider denotes the gain applied at the frequency band. Therefore, the knobs look like a graph depicting the equalizer’s response with respect to its frequency.


Frequency bands


The number of controls in a graphic equalizer depends upon the number of fixed frequencies it works on. In addition, the number of frequency channels of the equalizer depends upon its intended use. Consequently, a typical five-band graphic equalizer has sliders for five fixed frequency bands:

  • Low bass (30 Hz)
  • Low-bass (100 Hz)
  • Midrange (1 kHz)
  • Upper Midrange (10 kHz)
  • Treble (20 kHz)


Reducing resonant peaks


Graphic equalization reduces the effect of resonant peaks and dips in loudspeaker response. Furthermore, in an acoustic environment, it reduces the tendency of acoustic feedback to occur. As the overall gain (volume) of the sound system is turned up, feedback will first occur at the frequency (or frequencies)  where the system has a peak. It typically begins with the slight ringing and becomes a loud howl. When one uses a graphic equalizer to attenuate the first peak, the overall system gain increases until the next (formerly lower) peak begins to feedback. That peak is then attenuated using another graphic EQ band, and the system gain can be further increased. When the peaks have all been levelled to the extent possible with the EQ, the overall gain may usually increase from 6 dB to 10 dB above the initial gain before the feedback commences.


In conclusion


The graphic equalizer is a very useful tool, but it cannot substitute for good acoustics or for well-designed amplifier/loudspeaker systems. Excessive boosts, especially at the lower frequencies, drains much of the available amplifier power, overstresses the drivers in the loudspeaker system, and reduces overall system headroom. Excessive cat takes out noticeable portions of the program along with the desired response peak of the noise component.


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